On triazoles XLIV [1]. synthesis of new ring systems containing imidazo[2′,1′:3,4] [1,2,4] triazolo [1,5‐a]pyrimidine and imidazo[1′,2′:2,3][1,2,4]triazolo[1,5‐a]pyrimidine skeleton

Dedicated to Dr. Janos Csaszar on the occasion of his 70th birthday Ring transformation of 2-cyanoimido-3-methyl-1,3-oxazolidine (10) yielded 5-amino-3-[N-(2-hydrox-yethyl)-N-methyl]amino-1H-1,2,4-triazole (6) that was ring closed with different β-keto esters to 2-[N-(2-hydroxyethyl)-N-methyl]amino-1,2,4-triazolo[1,5-a]pyrimidinones (4). Cyclisation of derivatives 4 led to imidazo[2′,1′:3,4][1,2,4]triazolo[1,5-a]pyrimidines (2) and imidazo[1′,2′:2,3][1,2,4]triazolo[1,5-a]pyrim-idines (3) representing 10 novel ring systems. Besides spectroscopical evidence of structure of derivatives 2 and 3 X-ray diffraction analysis of derivative 2b was also performed.